The more you require to do this - walk to the park, a lawn, no noise - the less you will do it. In reality you could be locked in a prison and still do it.

You can close your eyes. Tricky if it's noisy - but then that's an issue in itself.

Oxygenated air is all you need

as the author points out, even thought in your own mind is a source of distraction and you can't run away from that.

Fundamentally you can be at ease with city noise just like you can be with mental distraction. One of the big misconceptions about meditation for example tends to be that it's about avoiding or actively quieting noise be that internal or external. It's not about changing the content of your conscious experience but your relationship to it.